This invention relates to a method and device for removing stones from the ureter and more particularly relates to a method and device for use with extracorporeal shock wave lithotripsy.
Extracorporeal shock wave lithotripsy is used to pulverize a stone which has been isolated between the balloons of a two balloon, four lumen catheter that can be inserted over a wire guide. A fluid is injected into the isolation area to enhance the effect of an extracorporeal shock wave on the stone. Upon selective deflation of one of the balloons (while leaving the other balloon inflated), the fluid is used to wash the pulverized stone material from the isolation area prior to further subjecting the stone to extracorporeal shock waves.
It is common for stones to be formed in the renal calyces which pass into and become lodged within the ureter of an individual. Stones lodged in the ureter often cause blockage of urine produced by the kidneys, causing ureteral colic to develop which may result in severe pain to the individual. physicians prefer to avoid surgery involving incisions of the ureter in an effort to remove these stones because of the dangers and complications which might arise from such surgery. In an effort to avoid the dangers associated with major surgery, physicians have developed many different methods of treatment for ureteral stones.
Among the various methods developed to treat ureteral stones has been to prescribe spasmolytic drugs in an effort to decrease spasms in the smooth muscle of the ureteral wall which were believed to prevent passage of the stone and passage of urine around the stone. However, these spasmolytic drugs have not proven to be substantially effective in aiding a ureteral stone to be passed by the individual. Another treatment for ureteral stones is to prescribe an increase in fluid intake in hope that the increased fluid intake will cause an increased urine production which would increase the pressure above the ureteral stone thereby facilitating passage of the stone. Increased fluid intake has proven to be an ineffective means of treating ureteral stones, and in fact may result in an increase of severity of ureteral colic.
Various devices exist which are designed to extract ureteral stones without major surgery. For example, the Dormia ureteral stone dislodger uses a catheter with a retractable spring wire mechanism. The Dormia stone dislodger uses a spring wire mechanism to form a basket for entrapment of the ureteral stone. Upon entrapment of the ureteral stone, the catheter with the stone in the basket is removed through the urinary tract. This type of dislodger is effective for extraction of small ureteral stones in the lower third of the ureter.
Another type of ureteral stone extractor is a catheter with two inflatable balloons which are manipulated so that the stone is between the balloons and is then slowly withdrawn with the lower balloon acting as a dilator and the upper balloon pushing the stone toward the bladder.
Yet a further type of ureteral stone extractor with two balloons is disclosed in U.S. Pat. No. 4,295,464 to Shihata. Shihata uses an inner dislodger catheter which is slidably received within a larger outer dilator catheter. The dislodger catheter is small enough to pass beyond and arrested stone in the ureter, whereupon the balloon on the dislodger catheter may be inflated. The larger outer dilator catheter also has a balloon which ma be inflated to dilate the ureter below the stone so that the dislodger catheter may be used to apply downward force upon the stone sufficient to dislodge it from the ureteral wall. The present invention does not seek to dislodge or extract the stone from the ureter while the stone is still intact. Thus, the chances of damaging the ureter with longitudinal frictional forces applied by inflated balloons or by a stone is decreased.
The present invention relies upon extracorporeal shock waves which are directed through the body to pulverize a stone within the ureter. Typically, an extracorporeal shock wave lithotripsy patient is submerged in a bath and an ultrasonic transducer is used to transmit ultrasonic shock wave through the body directed at a stone within the ureter. The ultrasonic shock waves create forces and vibrations within the stone which cause the stone to disintegrate into small parts which may then be passed easily by the patient through the ureter and into the bladder. Many extracorporeal shock wave lithotripsy centers practice placing a ureteral catheter next to a ureteral stone. Creating some space in the ureter around the stone helps the energy from the shock waves get to the stone. The present invention improves upon extracorporeal shock wave lithotripsy by providing a two balloon multilumen catheter designed to be inserted over a wire guide which has been positioned in the ureter. The catheter is inserted over the wire guide until the balloons are upon opposite sides of the stone. The balloons are then independently inflated to localize the stone between the balloons. The catheter also has a side opening lumen with the side openings located between the balloons so that fluids can be injected through the catheter into the cavity defined by the walls of the balloon and the ureter. The fluid aids in the transmission of the ultrasonic shock waves so that they pulverize the stone more effectively. When the stone is subjected to the extracorporeal shock waves, fragments are broken off of the stone which are small enough to pass through the ureter into the bladder. At this point, the proximate balloon (that balloon located in the ureter closer to the bladder than the other balloon) is deflated and fluid is injected through the side opening lumen to wash fragments of the stone into the bladder. Upon washing the smaller fragments into the bladder, the proximate lumen may again be inflated and fluid injected into the cavity between the balloons so that the stone can again be subjected to extracorporeal shock waves. This process is repeated until the entire stone has been pulverized and washed out of the ureter whereupon the catheter is withdrawn from the patient.
The present invention does not require a tugging force on the ureter which may cause damage as is required by various other stone extraction methods. Also, the standard extracorporeal shock wave lithotripsy is improved by providing a transmission fluid surrounding the stone to be pulverized and by localizing the area within which the shock waves need to be concentrated.